Clamping and transfer device for elongate articles

ABSTRACT

A clamping and transfer device for elongate articles, comprising a tubular clamping member which is radially contractible, disposed in a hollow piston slidable in a housing. Fluid pressure applied between the piston and the clamping member compresses the member onto an article which is then transferred by movement of the piston.

United States Patent 1191 Knights Dec. 17, 1974 CLAMPING AND TRANSFER DEVICE FOR [56] References Cited ELONGATE ARTICLES UNITED STATES PATENTS [75] Inventor: Richard Northan Knights, 3,010,568 11/1961 Annegarn 226/150 X 7 Gloucester, England 3,133,469 5/1964 Ljunberg 226/150 X [73] Asslgnee: l f M l lnflusmes (Kynoch) Primary Examiner- Richard A. Schacher Limited, Birmingham,

Attorney, Agent, or Flrm-Cushman, Darby & warwlckshlre, England Cushman [22] Filed: Aug. 13, 1973 App]. No.: 387,726

Foreign Application Priority Data Aug. 25, 1972 Great Britain 39704/72 [57] ABSTRACT A clamping and transfer devicefor elongate articles, comprising a tubular clamping member which is' radially contractible, disposed in a hollow piston slidable in a housing. Fluid pressure applied between the piston and the clamping member compresses the member onto an article which is then transferred by movement of the piston.

7 Claims, 3 Drawing Figures 48 Eli 46 j 32 3e 29 27 i 1 33 42 47 28 37 I7 3332 W11: 2 23 21 14s, I Mu H I312: I I5 will/A 31 g P; 22 45 "f t i PMENTEL UUJ 1 71974 SHEET 10? 3 CLAMPING AND TRANSFER DEVICE FOR ELONGATE ARTICLES BACKGROUND OF THE INVENTION This invention relates to clamping and transfer de- SUMMARY OF THE INVENTION According to the present invention, a clamping and transfer device is provided for transferring tube, rod or like articles in a direction longitudinally of the article, the device comprising an article-engaging tubular clamping member which is radially contractible, the clamping member being disposed in a bore of a hollow piston with end portions of the clamping member fluidtightly mounted in'respective end portions of the piston; a housing comprising a bore wherein the piston is slidably mounted for longitudinal movement therealong, the housing having fluid-supply passageways for supply of fluid to move the piston in both senses of longitudinal movement, the housing further comprising a fluid supply channel arranged for communication with an orifice in the piston throughout movement of the piston in the housing whereby fluid can be supplied between the piston and the clamping member thereby to pressurise and radially to compress the clamping member onto an article when the piston is moving in one sense of direction, and whereby fluid can be returned from between the piston and the clamping member to release pressure on the clamping member whilst the piston is moving in the other sense of direction.

Although the tubular clamping member may be merely a flexible hose, it is preferable that a clamping member is provided having a series of circumferentially spaced, longitudinally extending slots, and a flexible resilient sleeve is provided closely surrounding the slotted portion.

The clamping member may, alternatively, be formed of individual axially extending strips or wires anchored at their ends in annular collars.

Advantageously, the clamping member is formed by providing a series of longitudinal slots in a tube, and increasing the width of the slots at their end portions.

Advantageously, an annular space is provided between the clamping member or sleeve and the surface of the bore of the piston for rapid application of fluid pressure to the clamping member.

Preferably also, resilient means are provided between the clamping member and a fixed support to operate in an axial direction of the clamping member so as to accommodate flexing of the clamping member and thereby maintain the clamping member under tension.

Conveniently, the resilient means comprises concavo-convex, spring washers.

Advantageously, the piston comprises an external flange intermediate the ends of the piston, the flange being slidably engaged with and movable along part of the bore of the housing, and the fluid supply passageways opening into the bore at end regions of said part of the bore.

The supply of fluid to move the piston is preferably controlled by an electro-hydraulic servo valve, the valve receiving electric control signals from a position transducer of which the armature is connected to the hollow piston for movement therewith.

Also according to the present invention, an apparatus is provided for transferring tube, rod or like articles in a direction longitudinally of the article, the apparatus comprising two devices as defined above disposed in tandem, the pistons being axially aligned one with the other and arranged for relative axial movement with respect to one another, the devices being electrically interconnected so that one device is in an article release condition whilst the other device is in an article clamping and transferring condition.

The invention also includes a method of transferring tube, rod or like articles in a direction longitudinally of the article, comprising providing two devices as defined above in tandem, with the pistons of the devices axially aligned one with the other and arranged for relative axial movement with respect to one another, introducing one of said articles into the two devices, causing one of the devices to be in an article release condition whilst the other device clampsand transfers the article longitudinally thereof, causing said one device to clamp the article, causing said other device to release the article, and causing said one device to transfer the article longitudinally thereof.

' BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which:

FIG. 1 is an axial cross-sectional view of a clamping and transfer device;

FIG. 2 is a perspective view of an apparatus for transferring tube and incorporating two devices shown in FIG. 1; and

FIG. 3 shows schematically the successive clamping action and relative positions of the two devices of the apparatus during one cycle.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of the drawings, a clamping and transfer device 10 comprises an article-engaging tubular clamping member 11 which has a series of circumferentially spaced and longitudinally extending narrow slots 12 in its annular wall. The wall thickness of the tube in the region of the slots is sufficiently thin that the wall can resiliently flex radially inwardly. Each end portion of each slot is increased in width over a short distance as indicated at 13. The end portions 14,15 of the clamping member 11 each have a greater wall thickness in which an outer circumferential recess is fomied to receive an O-ring seal 16.

The end portion 14 has an endflange which provides an abutment for the outer face of a cup-shaped member 17. The end portion 15 has an outer circumferential recess to receive a collar 18 which supports the outer end of a series of spring washers 19 which operate in an axial direction of the clamping member to provide a resilient means between the collar and a counterbored support 20 through which the end portion 15 is movable. The spring washers l9 maintain the slotted clamping member 11 permanently under axial tension whilst allowing the clamping member to contract and expand slightly in a longitudinal sense during radial movement of the slotted portion.

A flexible resilient sleeve 21 formed from rubber tubing closely surrounds the slotted portion of the clamping member 11 and also a short distance of the clamping member beyondthe slotted portion at each end thereof, terminating short of the O-ring seals 16.

The clamping member 11 and the sleeve 21 are disposed in the bore of a hollow piston 22 of which end portions are in fluid tight engagement with the end portions 14,15 of the clamping member by virtue of the O- ring seals 16. The ends of the piston are disposed in the cup-shaped member 17 and the support 20.

It will be seen in the drawing that an annular space 23 is formed between the length of sleeve 21 which covers the major portion of the slotted length of the clamping member 11, and the inner surface of the piston 22.

The piston comprises a series of radial orifices 24 to provide communication from outside the piston to the annular space 23. The piston also comprises an external flange 25, this flange being recessed to accommodate seals 26.

The'piston is slidably mounted in a bore of a housing which is of composite construction.

The housing is constituted by a cylinder 27 having a bore 28 along which the flange 25 of the piston reciprocates. The bore 28 opens at each end into a recess which receives a bush 29. Each bush has an external peripheral seal 30 and the bore of the bush has a series of spaced apart shallow grooves 31. Circumferential seals 32 for the piston are located in collars 33, the left hand collar being retained by an end plate 34 bolted to the end of the cylinder 27, an additional sealing ring 35 being disposed in the end plate.

The collar 33 at the right hand end of the cylinder is retained by a valve block 36 which is bolted at side flanges (not shown) to the end of the cylinder 27, the block incorporating sealing rings 37 for engagement with the piston. The valve block 36 has a bore 38 of slightly larger diameter than that of the outside of the part of the piston which is movable through the block so as to provide an annular air supply channel 39 in the housing for communication with the orifices 24 in the piston throughout reciprocation of the piston. Passageways 40 for exhausted air are also formed in the valve block.

On the upper surface of the valve block there are mounted four pneumatic valves 41 coupled in parallel and controlled by a solenoid-operated valve 59 (shown in FIG. 2) for controlling the supply of pressurised air to four passageways 42 which'open into the annular channel 39 at intervals therealong. A plurality of valves 41 is employed since a single valve for the required flow may not have the low time constant for high speed operation due to its higher inertia.

A guide pin 43 is secured at one end in the free end face of the valve block 36 and below the piston so as to extend parallel with the piston, the pin being slidable in a bush 44 secured in a plate 45 which is mounted on and depends from the end portion of the piston. The cooperation of the pin 43 and the plate 45 prevents rotational movement of the piston.

The cylinder 27 is carried in a support 46 of which the upper portion comprises two passageways 47 which are aligned with passageways 47a in the cylinder to open into the respective ends of the bore 28 of the cylport in communication with the nozzles 52 and with the ends of the spool and, as required, with outlets to the I passageways 47 in the support 46 and thus with the bore 28 of cylinder 27. With no electric signal applied to the valve the system is balanced, oil pressure being applied to the nozzles 52 and to the ends of the spool, but the outlets from the valve being closed off by the spool.

When an electric signal is applied to the electromagnetic means 50, 51, the signal causes a proportionate deflection of the plate 49 towards one or the other of the nozzles 52. The nozzle which is approached by the plate 49 has its oil flow restricted thereby causing an increase in pressure which is transmitted to the appropriate end of the spool. The spool is thus moved to uncover a respective'outlet in the valve and allow oil to pass to the bore 28 to act against the appropriate side of the flange 25 and thus'move the piston 22. An electric signal of opposite sense will reverse the oil flow and cause the piston 22 to move in the opposite direction. The piston 22 is thus movable in proportion to the electric control signal applied to the servo valve 48.

The electric'signals are provided by an input voltage which varies with the feedback from a position transducer 53 of which the body 54 is secured in arms 55 of the support 46, and the armature 56 is secured at one end to the plate 45 so that the armature moves in unison with the piston 22. When the feedback from the transducer approaches the input voltage, the valve 48 is balanced.

Considering now the operation of the device and assuming an article in the form of a length of plastic tube is to be transferred longitudinally, the tube is initially introduced into the slotted clamping member 11. Operation of the solenoid valve 59 opens the pneumatic valves 41 to allow pressurised air to flow through the passageways 42 and into the annular channel 39, then through the orifices 24 and into the annular space 23 whereupon the sleeve 21 is externally pressurised. The pressure on the sleeve 21 is transmitted to the clamping member 11 which, by virtue of its slotted construction, is compressed radially inwardly onto the plastics tube.

An input voltage is fed to the valve 48 via an amplifier and a summing device which receives a feedback from the position transducer to effect movement of the piston 22 as described above which advances the plastics tube in proportion to the electric signal applied to the valve. When the signal is reduced to zero, the valve 48 is restored to its central or balanced position.

The valves 41 are subsequently closed, and the air in the annular space 23 is exhausted through the passageways 40 to atmosphere, thereby releasing the clamping member 11 from the plastics tube.

A further signal to the valve 48 causes the piston 22 to be returned to its initial position in readiness for a further transfer of tube.

For rapid and accurate incremental feeding of the plastics tube it is necessary to provide a clamping means to hold the article, in this embodiment the plastics tube, whilst the clamping member 11 is released from the tube. This is conveniently achieved by providing an apparatus with two devices 10,10a in tandem as shown in FIG. 2 and introducing a plastics tube 57 into the two devices so that one device clamps and feeds the tube by half the required increment of feed whilst the other device is released from the tube and is returning to its tube-engaging position in readiness to clamp and move the tube the remaining half of the required feed, so that the tube is never free of one or other of the devices.

The two devices 10,10a are mounted on a prefabricated structure 58 with the clamping members 11 arranged coaxially one with the other, one device a being arranged oppositely, end for end, with respect to the other device 10.

Each device is electrically offset to give a zero-input signal to the respective valve 48, ie the valve being in its balanced state, when the piston 22 is 3mm from the end of its stroke. An input signal equivalent to the required stroke of each piston is always applied to one device, the input being switched from one device to the other. The control of the two devices is achieved by a sequence register.

The air pressure in the annular spaces 23 is monitored so that when one device is balanced and the tube in that device is stationary preparatory to the tube being clamped, the clamping pressure must achieve adequate grip before the pressure in the other device is reduced sufficiently to release the tube. As the tube is released, in one device, the input signal is switched to the other device to initiate movement of its piston to feed the plastic tube.

One cycle of tube clamping and transferring operations is shown schematically in FIG. 3. In the first stage, the pistons of the two devices 10,10a are at mutually remote positions, the device 10 being in a tube clamping position andthe device 10a in a tube release position.

In the second stage, the pistons of both devices move towards one another, the piston of device 10 transferring the tube by half the required incremental feed.

At the third stage, the device 10a is caused to clamp the tube in addition to the device 10.

At the fourth stage, the device 10 releases the tube whilst the device 10a remains in a tube clamping position.

In the fifth stage, the pistons of both devices move away from one another, the piston of device 10a transferring the tube by the remaining half of the required incremental feed. I

I claim:

1. A clamping and transfer device for transferring tube, rod or like articles in a direction longitudinally of the article, the device comprising a housing having a bore therein, a hollow piston slidably mounted in the bore for longitudinal movement therealong, fluidsupply passageways in the housing for supply of fluid to move the piston in both senses of longitudinal movement, and a radially contractible article-engaging tubular clamping member disposed within the follow piston with end portions of the clamping member fluid-tightly mounted in respect of end portions of the piston,

the improvement consisting in a valve block mounted on the housing and having a bore through which is movable part of the piston and which provides an annular fluid-supply channel, a plurality of orifices in the piston providing communication from the fluid-supply channel to between the piston and the clamping member throughout movement of the piston in the valve block, and valve means on the valve block connected to the annular fluid-supply channel, wherebyfluidcan be supplied between the piston and the clamping member thereby to pressurise and radially to compress the clamping member onto an article when the piston is moving in one sense of direction, and whereby fluid can be returned from between the piston and the clamping member to release pressure on the clamping member while the piston is moving in the other sense of direction.

2. A device according to claim 1 wherein the tubular clamping member has a series of circumferentially spaced, longitudinally extending slots, and a flexible resilient sleeve closely surrounds the slotted portion.

3. A device according to claim 2 wherein the width of the slots is increased at their end portions.

4. A device according to claim 1 wherein an annular space is provided between the clamping member or sleeve and the surface of the bore of the piston for rapid application of fluid pressure to the clamping member.

5. A device according to claim 1 wherein resilient means are provided between the clamping member and a fixed support to operate in an axial direction of the clamping member so as to accommodate flexing of the clamping member and thereby maintain the clamping member under tension.

6. A device according to claim 1 wherein a supply of fluid to move the piston is controlled by an electrohydraulic servo valve, the valve receiving electric control signals from a position transducer of which the armature is connected to the hollow piston for movement therewith.

7. A device according to claim 1 wherein said valve means comprises a plurality of valves mounted on the valve block, each valve having a corresponding passageway leading therefrom to the annular fluid-supply channel. 

1. A clamping and transfer device for transferring tube, rod or like articles in a direction longitudinally of the article, the device comprising a housing having a bore therein, a hollow piston slidably mounted in the bore for longitudinal movement therealong, fluid-supply passageways in the housing for supply of fluid to move the piston in both senses of longitudinal movement, and a radially contractible article-engaging tubular clamping member disposed within the follow piston with end portions of the clamping member fluid-tightly mounted in respect of end portions of the piston, the improvement consisting in a valve block mounted on the housing and having a bore through which is movable part of the piston and which provides an annular fluid-supply channel, a plurality of orifices in the piston providing communication from the fluid-supply channel to between the piston and the clamping member throughout movement of the piston in the valve block, and valve means on the valve block connected to the annular fluid-supply channel, whereby fluid can be supplied between the piston and the clamping member thereby to pressurise and radially to compress the clamping member onto an article when the piston is moving in one sense of direction, and whereby fluid can be returned from between the piston and the clamping member to release pressure on the clamping member while the piston is moving in the other sense of direction.
 2. A device according to claim 1 wherein the tubular clamping member has a series of circumferentially spaced, longitudinally extending slots, and a flexible resilient sleeve closely surrounds the slotted portion.
 3. A device according to claim 2 wherein the width of the slots is increased at their end portions.
 4. A device according to claim 1 wherein an annular space is provided between the clamping member or sleeve and the surface of the bore of the piston for rapid application of fluid pressure to the clamping member.
 5. A device according to claim 1 wherein resilient means are provided between the clamping member and a fixed support to operate in an axial direction of the clamping member so as to accommodate flexing of the clamping member and thereby maintain the clamping member under tension.
 6. A device according to claim 1 wherein a supply of fluid to move the piston is controlled by an electro-hydraulic servo valve, the valve receiving electric control signals from a position transducer of which the armature is connected to the hollow piston for movement therewith.
 7. A device according to claim 1 wherein said valve means comprises a plurality of valves mounted on the valve block, each valve having a corresponding passageway leading therefrom to the annular fluid-supply channel. 